1 /* 2 * pseries CPU Hotplug infrastructure. 3 * 4 * Split out from arch/powerpc/platforms/pseries/setup.c 5 * arch/powerpc/kernel/rtas.c, and arch/powerpc/platforms/pseries/smp.c 6 * 7 * Peter Bergner, IBM March 2001. 8 * Copyright (C) 2001 IBM. 9 * Dave Engebretsen, Peter Bergner, and 10 * Mike Corrigan {engebret|bergner|mikec}@us.ibm.com 11 * Plus various changes from other IBM teams... 12 * 13 * Copyright (C) 2006 Michael Ellerman, IBM Corporation 14 * 15 * This program is free software; you can redistribute it and/or 16 * modify it under the terms of the GNU General Public License 17 * as published by the Free Software Foundation; either version 18 * 2 of the License, or (at your option) any later version. 19 */ 20 21 #include <linux/kernel.h> 22 #include <linux/interrupt.h> 23 #include <linux/delay.h> 24 #include <linux/sched.h> /* for idle_task_exit */ 25 #include <linux/cpu.h> 26 #include <linux/of.h> 27 #include <asm/prom.h> 28 #include <asm/rtas.h> 29 #include <asm/firmware.h> 30 #include <asm/machdep.h> 31 #include <asm/vdso_datapage.h> 32 #include <asm/xics.h> 33 #include "plpar_wrappers.h" 34 #include "offline_states.h" 35 36 /* This version can't take the spinlock, because it never returns */ 37 static struct rtas_args rtas_stop_self_args = { 38 .token = RTAS_UNKNOWN_SERVICE, 39 .nargs = 0, 40 .nret = 1, 41 .rets = &rtas_stop_self_args.args[0], 42 }; 43 44 static DEFINE_PER_CPU(enum cpu_state_vals, preferred_offline_state) = 45 CPU_STATE_OFFLINE; 46 static DEFINE_PER_CPU(enum cpu_state_vals, current_state) = CPU_STATE_OFFLINE; 47 48 static enum cpu_state_vals default_offline_state = CPU_STATE_OFFLINE; 49 50 static int cede_offline_enabled __read_mostly = 1; 51 52 /* 53 * Enable/disable cede_offline when available. 54 */ 55 static int __init setup_cede_offline(char *str) 56 { 57 if (!strcmp(str, "off")) 58 cede_offline_enabled = 0; 59 else if (!strcmp(str, "on")) 60 cede_offline_enabled = 1; 61 else 62 return 0; 63 return 1; 64 } 65 66 __setup("cede_offline=", setup_cede_offline); 67 68 enum cpu_state_vals get_cpu_current_state(int cpu) 69 { 70 return per_cpu(current_state, cpu); 71 } 72 73 void set_cpu_current_state(int cpu, enum cpu_state_vals state) 74 { 75 per_cpu(current_state, cpu) = state; 76 } 77 78 enum cpu_state_vals get_preferred_offline_state(int cpu) 79 { 80 return per_cpu(preferred_offline_state, cpu); 81 } 82 83 void set_preferred_offline_state(int cpu, enum cpu_state_vals state) 84 { 85 per_cpu(preferred_offline_state, cpu) = state; 86 } 87 88 void set_default_offline_state(int cpu) 89 { 90 per_cpu(preferred_offline_state, cpu) = default_offline_state; 91 } 92 93 static void rtas_stop_self(void) 94 { 95 struct rtas_args *args = &rtas_stop_self_args; 96 97 local_irq_disable(); 98 99 BUG_ON(args->token == RTAS_UNKNOWN_SERVICE); 100 101 printk("cpu %u (hwid %u) Ready to die...\n", 102 smp_processor_id(), hard_smp_processor_id()); 103 enter_rtas(__pa(args)); 104 105 panic("Alas, I survived.\n"); 106 } 107 108 static void pseries_mach_cpu_die(void) 109 { 110 unsigned int cpu = smp_processor_id(); 111 unsigned int hwcpu = hard_smp_processor_id(); 112 u8 cede_latency_hint = 0; 113 114 local_irq_disable(); 115 idle_task_exit(); 116 xics_teardown_cpu(); 117 118 if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) { 119 set_cpu_current_state(cpu, CPU_STATE_INACTIVE); 120 if (ppc_md.suspend_disable_cpu) 121 ppc_md.suspend_disable_cpu(); 122 123 cede_latency_hint = 2; 124 125 get_lppaca()->idle = 1; 126 if (!get_lppaca()->shared_proc) 127 get_lppaca()->donate_dedicated_cpu = 1; 128 129 while (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) { 130 extended_cede_processor(cede_latency_hint); 131 } 132 133 if (!get_lppaca()->shared_proc) 134 get_lppaca()->donate_dedicated_cpu = 0; 135 get_lppaca()->idle = 0; 136 137 if (get_preferred_offline_state(cpu) == CPU_STATE_ONLINE) { 138 unregister_slb_shadow(hwcpu); 139 140 /* 141 * Call to start_secondary_resume() will not return. 142 * Kernel stack will be reset and start_secondary() 143 * will be called to continue the online operation. 144 */ 145 start_secondary_resume(); 146 } 147 } 148 149 /* Requested state is CPU_STATE_OFFLINE at this point */ 150 WARN_ON(get_preferred_offline_state(cpu) != CPU_STATE_OFFLINE); 151 152 set_cpu_current_state(cpu, CPU_STATE_OFFLINE); 153 unregister_slb_shadow(hwcpu); 154 rtas_stop_self(); 155 156 /* Should never get here... */ 157 BUG(); 158 for(;;); 159 } 160 161 static int pseries_cpu_disable(void) 162 { 163 int cpu = smp_processor_id(); 164 165 set_cpu_online(cpu, false); 166 vdso_data->processorCount--; 167 168 /*fix boot_cpuid here*/ 169 if (cpu == boot_cpuid) 170 boot_cpuid = cpumask_any(cpu_online_mask); 171 172 /* FIXME: abstract this to not be platform specific later on */ 173 xics_migrate_irqs_away(); 174 return 0; 175 } 176 177 /* 178 * pseries_cpu_die: Wait for the cpu to die. 179 * @cpu: logical processor id of the CPU whose death we're awaiting. 180 * 181 * This function is called from the context of the thread which is performing 182 * the cpu-offline. Here we wait for long enough to allow the cpu in question 183 * to self-destroy so that the cpu-offline thread can send the CPU_DEAD 184 * notifications. 185 * 186 * OTOH, pseries_mach_cpu_die() is called by the @cpu when it wants to 187 * self-destruct. 188 */ 189 static void pseries_cpu_die(unsigned int cpu) 190 { 191 int tries; 192 int cpu_status = 1; 193 unsigned int pcpu = get_hard_smp_processor_id(cpu); 194 195 if (get_preferred_offline_state(cpu) == CPU_STATE_INACTIVE) { 196 cpu_status = 1; 197 for (tries = 0; tries < 5000; tries++) { 198 if (get_cpu_current_state(cpu) == CPU_STATE_INACTIVE) { 199 cpu_status = 0; 200 break; 201 } 202 msleep(1); 203 } 204 } else if (get_preferred_offline_state(cpu) == CPU_STATE_OFFLINE) { 205 206 for (tries = 0; tries < 25; tries++) { 207 cpu_status = smp_query_cpu_stopped(pcpu); 208 if (cpu_status == QCSS_STOPPED || 209 cpu_status == QCSS_HARDWARE_ERROR) 210 break; 211 cpu_relax(); 212 } 213 } 214 215 if (cpu_status != 0) { 216 printk("Querying DEAD? cpu %i (%i) shows %i\n", 217 cpu, pcpu, cpu_status); 218 } 219 220 /* Isolation and deallocation are definitely done by 221 * drslot_chrp_cpu. If they were not they would be 222 * done here. Change isolate state to Isolate and 223 * change allocation-state to Unusable. 224 */ 225 paca[cpu].cpu_start = 0; 226 } 227 228 /* 229 * Update cpu_present_mask and paca(s) for a new cpu node. The wrinkle 230 * here is that a cpu device node may represent up to two logical cpus 231 * in the SMT case. We must honor the assumption in other code that 232 * the logical ids for sibling SMT threads x and y are adjacent, such 233 * that x^1 == y and y^1 == x. 234 */ 235 static int pseries_add_processor(struct device_node *np) 236 { 237 unsigned int cpu; 238 cpumask_var_t candidate_mask, tmp; 239 int err = -ENOSPC, len, nthreads, i; 240 const u32 *intserv; 241 242 intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len); 243 if (!intserv) 244 return 0; 245 246 zalloc_cpumask_var(&candidate_mask, GFP_KERNEL); 247 zalloc_cpumask_var(&tmp, GFP_KERNEL); 248 249 nthreads = len / sizeof(u32); 250 for (i = 0; i < nthreads; i++) 251 cpumask_set_cpu(i, tmp); 252 253 cpu_maps_update_begin(); 254 255 BUG_ON(!cpumask_subset(cpu_present_mask, cpu_possible_mask)); 256 257 /* Get a bitmap of unoccupied slots. */ 258 cpumask_xor(candidate_mask, cpu_possible_mask, cpu_present_mask); 259 if (cpumask_empty(candidate_mask)) { 260 /* If we get here, it most likely means that NR_CPUS is 261 * less than the partition's max processors setting. 262 */ 263 printk(KERN_ERR "Cannot add cpu %s; this system configuration" 264 " supports %d logical cpus.\n", np->full_name, 265 cpumask_weight(cpu_possible_mask)); 266 goto out_unlock; 267 } 268 269 while (!cpumask_empty(tmp)) 270 if (cpumask_subset(tmp, candidate_mask)) 271 /* Found a range where we can insert the new cpu(s) */ 272 break; 273 else 274 cpumask_shift_left(tmp, tmp, nthreads); 275 276 if (cpumask_empty(tmp)) { 277 printk(KERN_ERR "Unable to find space in cpu_present_mask for" 278 " processor %s with %d thread(s)\n", np->name, 279 nthreads); 280 goto out_unlock; 281 } 282 283 for_each_cpu(cpu, tmp) { 284 BUG_ON(cpu_present(cpu)); 285 set_cpu_present(cpu, true); 286 set_hard_smp_processor_id(cpu, *intserv++); 287 } 288 err = 0; 289 out_unlock: 290 cpu_maps_update_done(); 291 free_cpumask_var(candidate_mask); 292 free_cpumask_var(tmp); 293 return err; 294 } 295 296 /* 297 * Update the present map for a cpu node which is going away, and set 298 * the hard id in the paca(s) to -1 to be consistent with boot time 299 * convention for non-present cpus. 300 */ 301 static void pseries_remove_processor(struct device_node *np) 302 { 303 unsigned int cpu; 304 int len, nthreads, i; 305 const u32 *intserv; 306 307 intserv = of_get_property(np, "ibm,ppc-interrupt-server#s", &len); 308 if (!intserv) 309 return; 310 311 nthreads = len / sizeof(u32); 312 313 cpu_maps_update_begin(); 314 for (i = 0; i < nthreads; i++) { 315 for_each_present_cpu(cpu) { 316 if (get_hard_smp_processor_id(cpu) != intserv[i]) 317 continue; 318 BUG_ON(cpu_online(cpu)); 319 set_cpu_present(cpu, false); 320 set_hard_smp_processor_id(cpu, -1); 321 break; 322 } 323 if (cpu >= nr_cpu_ids) 324 printk(KERN_WARNING "Could not find cpu to remove " 325 "with physical id 0x%x\n", intserv[i]); 326 } 327 cpu_maps_update_done(); 328 } 329 330 static int pseries_smp_notifier(struct notifier_block *nb, 331 unsigned long action, void *node) 332 { 333 int err = 0; 334 335 switch (action) { 336 case OF_RECONFIG_ATTACH_NODE: 337 err = pseries_add_processor(node); 338 break; 339 case OF_RECONFIG_DETACH_NODE: 340 pseries_remove_processor(node); 341 break; 342 } 343 return notifier_from_errno(err); 344 } 345 346 static struct notifier_block pseries_smp_nb = { 347 .notifier_call = pseries_smp_notifier, 348 }; 349 350 #define MAX_CEDE_LATENCY_LEVELS 4 351 #define CEDE_LATENCY_PARAM_LENGTH 10 352 #define CEDE_LATENCY_PARAM_MAX_LENGTH \ 353 (MAX_CEDE_LATENCY_LEVELS * CEDE_LATENCY_PARAM_LENGTH * sizeof(char)) 354 #define CEDE_LATENCY_TOKEN 45 355 356 static char cede_parameters[CEDE_LATENCY_PARAM_MAX_LENGTH]; 357 358 static int parse_cede_parameters(void) 359 { 360 memset(cede_parameters, 0, CEDE_LATENCY_PARAM_MAX_LENGTH); 361 return rtas_call(rtas_token("ibm,get-system-parameter"), 3, 1, 362 NULL, 363 CEDE_LATENCY_TOKEN, 364 __pa(cede_parameters), 365 CEDE_LATENCY_PARAM_MAX_LENGTH); 366 } 367 368 static int __init pseries_cpu_hotplug_init(void) 369 { 370 struct device_node *np; 371 const char *typep; 372 int cpu; 373 int qcss_tok; 374 375 for_each_node_by_name(np, "interrupt-controller") { 376 typep = of_get_property(np, "compatible", NULL); 377 if (strstr(typep, "open-pic")) { 378 of_node_put(np); 379 380 printk(KERN_INFO "CPU Hotplug not supported on " 381 "systems using MPIC\n"); 382 return 0; 383 } 384 } 385 386 rtas_stop_self_args.token = rtas_token("stop-self"); 387 qcss_tok = rtas_token("query-cpu-stopped-state"); 388 389 if (rtas_stop_self_args.token == RTAS_UNKNOWN_SERVICE || 390 qcss_tok == RTAS_UNKNOWN_SERVICE) { 391 printk(KERN_INFO "CPU Hotplug not supported by firmware " 392 "- disabling.\n"); 393 return 0; 394 } 395 396 ppc_md.cpu_die = pseries_mach_cpu_die; 397 smp_ops->cpu_disable = pseries_cpu_disable; 398 smp_ops->cpu_die = pseries_cpu_die; 399 400 /* Processors can be added/removed only on LPAR */ 401 if (firmware_has_feature(FW_FEATURE_LPAR)) { 402 of_reconfig_notifier_register(&pseries_smp_nb); 403 cpu_maps_update_begin(); 404 if (cede_offline_enabled && parse_cede_parameters() == 0) { 405 default_offline_state = CPU_STATE_INACTIVE; 406 for_each_online_cpu(cpu) 407 set_default_offline_state(cpu); 408 } 409 cpu_maps_update_done(); 410 } 411 412 return 0; 413 } 414 arch_initcall(pseries_cpu_hotplug_init); 415